I just bought a 2014 Stingray (with 2150 miles) and I'm learning about it. Electronics is how I've made my living, so I'm wondering about the voltage. Idling at 45 degrees, it stays mostly above 15 volts, and as high as 15.6! I checked against a digital meter, and the display is accurate within a tenth volt.

A battery requires higher voltage to charge with lower temperatures, but I've never seen a system run this high. I would expect it to boil out the acid, killing the battery. At 45 degrees I'd expect about 14.5 volts.

What are other C7s showing?

Another question: what stores in the cutout in the battery cover? I put the funnel there, but it seems to be for something longer.

Dave

 

My voltage shows about the same as yours. Once the car is fully warmed up and just at a steady cruise you'll see it drop quite a bit. The C7 seems to have a much wider voltage operating range than most cars.

 

Alternator puts out what is needed and will vary based on a lot more than RPM. Same with your oil pump.

 

Nevertheless, a lead-acid battery requires a particular voltage range for a given temperature, and I have never seen one charge at such a high voltage. This will also greatly shorten incandescent lamp life. Fortunately our many LEDs are tolerant to high voltage. From Powerstream.com, at 50 degrees the "gassing" voltage is 14.82 volts, and any charging at that high rate should be used only with batteries that have their electrolyte replenished, unlike ours. Their point is that the acid mix will go down at that voltage, as vapor out the vent hose.

The alternator puts out a constant but temperature corrected voltage (if turning fast enough) regardless of the load. When there is more current, its job is to maintain that same voltage, thereby delivering more current. This function is unchanged from even the first car batteries.

This is in fact similar to the oil pump, because its job is to maintain a relatively constant pressure (voltage) while flow rate may change (current). With our LT1 the load changes with sprayers turning off and on, cam timing, and oil used to shut off the unused four cylinders. We also have the second, lower pressure pump to reduce load. (I WISH I could get the service manual, but I see it's not due for the '14 for another month. I always buy those and GM does a great job on how thorough they are.)

Dave

 

I found the answer to my second question about the indentation in the battery cover in another thread, namely a towing piece not used in the US. It is a good place to store that rarely-used funnel, though.

 

The charging system is now controlled by the computer and turns the system clear off when fully charged mine alternates from 12.8 to 14.4 last summer now I see 13.4 to 15.2 and was also concerned about boiling the water out. It has the ability to shut down less important systems if voltage in system is low for some reason. I wonder if there is a traditional reg in the Alt since I see such swing in voltage. Also the charger in the trunk seems to keep the battery at higher level than driving the car does!

Also looking at the of DTC's There is a PO562 low voltage and PO563 High voltage so I decided I was trying to out think my system when its doing fine. I'm also wanting factory manuals from Helms

 

During the bulk charge phase (short initial period after heavy discharge like starting your car) the voltage for the 12 volt nominal battery can safely be over 15 volts. This voltage shouldn't be maintained for an extended period of time and this level should not be applied to a near fully charged battery but for the scenario you describe it is not going to hurt the battery.

Recent GM vehicles I have owned vary the voltage quite a bit during operation and part of this is related to maximizing economy. My 2008 Cadillac CTS would show a charge voltage of 15.4-15.6 for a short time after start and would drop significantly then come back up in the 15 volt range again before dropping and repeating, I am sure this was a combination of charging and economy strategy. It would finally become fairly stable after a few hours of sustained driving, I checked into it and this was normal behavior as designed.

 

I notice on my 2015 Z-51, which is not my daily driver and often sits for days at a time, that it also seems to charge over 15v.on start up. However if I put a trickle on it during its off driving times, it charges below 14v. at first start...